EP0505826B1 - Méthode de commander à un instrument de mesure - Google Patents

Méthode de commander à un instrument de mesure Download PDF

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Publication number
EP0505826B1
EP0505826B1 EP92104102A EP92104102A EP0505826B1 EP 0505826 B1 EP0505826 B1 EP 0505826B1 EP 92104102 A EP92104102 A EP 92104102A EP 92104102 A EP92104102 A EP 92104102A EP 0505826 B1 EP0505826 B1 EP 0505826B1
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EP
European Patent Office
Prior art keywords
value
meter
driving method
frequency
output value
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Expired - Lifetime
Application number
EP92104102A
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German (de)
English (en)
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EP0505826A1 (fr
Inventor
Hiroshi C/O Rohm Co. Ltd. Murase
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Rohm Co Ltd
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Rohm Co Ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R7/00—Instruments capable of converting two or more currents or voltages into a single mechanical displacement
    • G01R7/04—Instruments capable of converting two or more currents or voltages into a single mechanical displacement for forming a quotient
    • G01R7/06—Instruments capable of converting two or more currents or voltages into a single mechanical displacement for forming a quotient moving-iron type
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P3/00—Measuring linear or angular speed; Measuring differences of linear or angular speeds
    • G01P3/42—Devices characterised by the use of electric or magnetic means
    • G01P3/44—Devices characterised by the use of electric or magnetic means for measuring angular speed
    • G01P3/48—Devices characterised by the use of electric or magnetic means for measuring angular speed by measuring frequency of generated current or voltage
    • G01P3/481—Devices characterised by the use of electric or magnetic means for measuring angular speed by measuring frequency of generated current or voltage of pulse signals
    • G01P3/489—Digital circuits therefor
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
    • G01R15/005—Circuits for altering the indicating characteristic, e.g. making it non-linear

Definitions

  • This invention relates to a method for driving a meter having a pointer actuated by a magnetic field.
  • the velocity or engine speed of a vehicle is usually indicated by a pointer of a speedmeter or a tachometer.
  • a cross-coil meter is widely used for this purpose.
  • FIG. 2 of the accompanying drawings shows the operation principle of such a cross-coil meter.
  • the cross-coil meter includes a magnet M and two exciting coils Ls and Lc.
  • the coils Ls, Lc generate magnetic fields having intensities according to currents supplied by a driving system (not shown). These two coils are arranged to be perpendicular to each other.
  • a combined magnetic field composed of the magnetic fields of these coils Ls, Lc is controlled by regulating the currents which are applied to these coils.
  • the magnet M is located so as to be actuated by the combined magnetic field. When it is actuated, the magnet M generates torque, angularly moving according to the torque.
  • a non-illustrated pointer is connected to the magnet M to deflect in response to the angular movement of the magnet M.
  • FIG. 3 of the accompanying drawings shows a speedometer for a vehicle.
  • a pointer I is connected to the magnet M of FIG. 2.
  • An angle ⁇ corresponds to the angle by which the magnet M is moved due to the combined magnetic field generated by the coils Ls, Lc.
  • a pulse output type sensor is usually used for detecting the vehicle or engine speed. Some speed sensors generate pulse signals having different frequencies according to detected speeds.
  • a cross-coil meter When a cross-coil meter is set in motion by an output from such a sensor, it is necessary to use a counter for counting the frequency of pulses, a modulator for performing the pulse width modulation (PWM) according to the counted results of the counter, a driver for supplying PWM-modulated currents to the coils Ls, Lc, and so forth.
  • PWM pulse width modulation
  • a driver for supplying PWM-modulated currents to the coils Ls, Lc, and so forth.
  • a ROM or the like should be used to correspond the counted frequencies with the deflection angle ⁇ .
  • variable inputs from the sensor are variable to a certain extent.
  • such variable inputs should preferably be stabilized to prevent unfavorable deflection of the pointer I.
  • the counted frequency of pulses are conventionally averaged in a specified period of time, so that the deflection angle ⁇ of the pointer is controlled by a mean value.
  • F in is an input frequency
  • F n-1 is a frequency which serves as a base for determining the deflection angle ⁇ at the time point n-1
  • F n-2 is another frequency serving as another base for determining the deflection angle ⁇ , and so forth.
  • a control circuit is already known to be used, for example, to drive a crossed coils meter.
  • a numeric signal is representative for the signal frequency and a clock frequency is used for determining the value thereof.
  • EP-A-0 413 891 discloses an input circuit to a crossed coils meter.
  • the input frequency is converted to a proportional current for the crossed coils meter. Further, the input current is made independent on the actual frequency in case said frequency is low.
  • JP-A-5957163 discloses a speed measuring apparatus wherein clocks are applied from a reference signal generation circuit.
  • a processing circuit computes the speed values and a memory circuit memorizes them.
  • FIG. 1 shows a driving system for operating a meter in accordance to the invention.
  • the driving system receives signals from a pulse output type sensor to drive a cross-coil meter 26.
  • Signals from the sensor are firstly counted by a binary counter 10, which recognizes a period of the received signals based on reference clock signals generated by a reference clock generator 12.
  • the binary counter 10 counts the number of pulses generated between the rise and immediate fall of the signals from the sensor.
  • T in a half period of the sensor signals is detected with specified precision.
  • the binary counter 10 may count the number of reference pulses generated between the fall and immediate rise of the signals from the sensor.
  • the binary counter 10 may also count intervals between falls of the signals from the sensor.
  • the driving system of FIG. 1 can perform these counting operations.
  • a latch 14 latches the counted results of the binary counter 10.
  • Latch timing corresponds to the timing of rise or fall of the signals from the sensor.
  • the rise or fall timing of the signals is selected as the latch timing depending on which of the three foregoing operations is executed by the binary counter 10.
  • the value latched by the latch 14 directly or indirectly represents the period T in of the signals outputted by the sensor. Since the period T in is a reciprocal of a frequency F in , the value latched by the latch 14 is a value of the frequency F in .
  • the reference clock signals are also supplied to a CPU 16 and PWM modulator 22 for synchronization, as described later.
  • the CPU 16 performs the calculations based on the value latched by the latch 14, i.e. data representing the period T in or frequency F in of the signal outputted by the sensor, thereby controlling the indication to be given by the cross-coil meter 26.
  • the CPU 16 performs its control operation according to a preset program. Specifically, the CPU 16 is connected to a ROM 20 for storing the calculation program.
  • the ROM 20 stores not only the calculation program but also various coefficients (such as ⁇ and ⁇ m ) to be used for the calculations.
  • the CPU 16 executes the control calculations while storing in RAM 18 intermediate aspects or results of the calculations.
  • the CPU 16 controls the indication of the cross-coil meter 26 as follows.
  • the CPU 16 reads the data latched by the latch 14.
  • the data represent the period T in or frequency F in of the signals outputted by the sensor as described above.
  • the CPU 16 determines the output value F n based on the period T in or frequency F in .
  • the CPU 16 determines the output value F n by using a response coefficient ⁇ .
  • the following formula is used for this purpose.
  • F in 1/T in (1)
  • ⁇ ⁇ F in /( ⁇ F in + 1)
  • F n ⁇ F n-1 + (1 - ⁇ )F in (3)
  • ⁇ is a constant.
  • the CPU 16 determines the output value F n based on the frequency F in by using the formulas (2) and (3).
  • the CPU 16 stores the output value F n as F n-1 in RAM 18. In other words, F n-1 is renewed in the RAM 18. The CPU 16 also calculates and outputs a value F m to be indicated.
  • the PWM modulator 22 has a register for storing the value F m to be indicated. This register is not shown in FIG. 1.
  • the value F m is calculated by using the weight-averaging formula (4).
  • F m ⁇ m F m-1 + (1 - ⁇ m )F n (4) where ⁇ m is a constant.
  • the CPU 16 uses the value F m to renew the contents of a register of the PWM modulator 22.
  • the PWM modulator 22 determines a deflection angle ⁇ of the cross-coil meter 26 based on the value F m which is calculated by the CPU 16 and stored in the register of the PWM modulator 22. As described above, the period or frequency of the pulse signals from the sensor corresponds to the value detected by the sensor, e.g. speed. Therefore, the CPU 16 calculates the value F m by using the foregoing formulas, determining the deflection angle ⁇ of the cross-coil meter 26 so that the detected value of the sensor is indicated by the cross-coil meter 26. The PWM modulator 22 determines the deflection angle ⁇ by referring to a table (not shown) in the memory.
  • the PWM modulator 22 generates two kinds of signals, sine and cosine signals, based on the deflection angle ⁇ , outputting these signals to a driver 28.
  • the driver 28 operates the cross-coil meter 26 in response to the received sine and cosine signals. Specifically, the PWM modulator 22 supplies the driver 28 with the sine and cosine signals representing the absolute values of sin ⁇ and cos ⁇ . Then, the driver 28 provides the two coils of the cross-coil meter 26 with currents having effective values corresponding to the two PWM signals, respectively.
  • the driver 28 requires information concerning the signs of sin ⁇ and cos ⁇ .
  • a steering logic 24 determines the signs of sin ⁇ and cos ⁇ based on the output value F n and the value F m (to be indicated), thereby supplying them to the driver 28. When the value F m to be indicated is in the first quadrant, both sin ⁇ and cos ⁇ are positive. Therefore, the steering logic 24 sends the driver 28 the signals denoting that the signals sin ⁇ and cos ⁇ are positive. Receiving the sine and cosine signals from the PWM modulator 22 and signals representing the signs of these signals, the driver 28 operates the cross-coil meter 26 accordingly.
  • the weight coefficient ⁇ in the formula (3) is determined according to the frequency F in when the CPU 16 calculates the output value F n .
  • the higher the frequency F in the less the cross-coil meter 26 is responsive to the input from the sensor so as to indicate the value F m precisely. It is therefore possible to overcome the inconvenience with conventional meters that the higher the input frequency F in , the more extensively the meter 26 tends to deflect its pointer.
  • the lower the frequency F in the more the meter 26 becomes responsive to the input from the sensor so as to give an accurate indication of the value F m .

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Nonlinear Science (AREA)
  • Measuring Frequencies, Analyzing Spectra (AREA)
  • Portable Nailing Machines And Staplers (AREA)
  • Control Of Stepping Motors (AREA)

Claims (9)

  1. Procédé de commande d'un appareil de mesure, comprenant les étapes de :
    - mesure de la période (Tin) ou de la fréquence (Fin) d'un signal de capteur de manière à obtenir une première valeur;
    - calcul d'une valeur de sortie (Fn) sur la base de ladite première valeur par combinaison d'une valeur de sortie (Fn-1) précédente et de ladite première valeur, les deux étant influencées par un poids (α) de manière que la fluctuation de la valeur de sortie (Fn) soit annulée lors de la mesure de fréquences élevés de signal de capteur, tandis que la fluctuation de la valeur de sortie (Fn) est augmentée lors de la mesure de fréquences faibles de signal de capteur;
    - calcul d'une valeur indicative (Fm) sur la base de ladite valeur de sortie (Fn) et d'une valeur d'indicative précédente (Fm-1); et
    - utilisation de ladite valeur indicative (Fm) pour commander un appareil de mesure (26, 28).
  2. Le procédé de commande d'appareil de mesure selon la revendication 1, caractérisée en ce que la valeur de sortie (Fn) est calculée par utilisation de la formule ci-après:

    F n = α F n-1 + (1 - α) F in
    Figure imgb0013

       dans laquelle Fn-1 est la valeur de sortie précédente, Fin la fréquence de signal de capteur et α est le poids.
  3. Le procédé de commande d'appareil de mesure selon la revendication 2, caractérisée en ce que le poids (α) est déterminé par la formule ci-après :

    α = β · F in /( βF in + 1)
    Figure imgb0014

       dans laquelle Fin est la fréquence de signal de capteur et β est une constante.
  4. Le procédé de commande d'appareil de mesure selon l'une des revendications 1 à 3, caractérisée en ce que ladite valeur indicative (Fm) est calculée par formation de la moyenne pondérée de la valeur indicative précédente (Fm-1) et de ladite valeur de sortie (Fn)
  5. Procédé de commande d'appareil de mesure selon la revendication 4, caractérisée en ce que la valeur indicative (Fm) est calculée pour utilisation de la formule ci-après :

    F m = α m F m-1 + (1- α m ) F n
    Figure imgb0015

       dans laquelle Fm-1 est la valeur indicative précédente, Fn est la valeur de sortie et αm est une constante.
  6. Le procédé de commande d'appareil de mesure selon l'une des revendications 1 à 5, caractérisée en ce que, pour mesurer la fréquence ou la période du signal de capteur, les signaux d'horloge de référence ayant une période de référence prédéterminée sont comptés dans les limites d'un nombre prédéterminé de périodes dudit signal de capteur.
  7. Le procédé de commande d'appareil de mesure selon l'une des revendications 1 à 6, caractérisée en ce que la valeur indicative (Fm) est utilisée pour déterminer un angle de déviation (Θ) d'un pointeur (1) dudit appareil de mesure (26, 28).
  8. Le procédé de commande d'appareil de mesure selon la revendication 7, caractérisée en ce que, en fonction de l'angle de déviation (Θ) déterminé, des valeurs effectives des courants d'excitation d'une pluralité de bobines d'excitation (Ls, Lc) sont calculées.
  9. Le procédé de commande d'un appareil de mesure selon la revendication 8, caractérisée en ce que les signes des courants d'excitation sont déterminés d'après l'angle de déviation (Θ) déterminé.
EP92104102A 1991-03-26 1992-03-10 Méthode de commander à un instrument de mesure Expired - Lifetime EP0505826B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP3061924A JP2525963B2 (ja) 1991-03-26 1991-03-26 メ―タ駆動装置
JP61924/91 1991-03-26

Publications (2)

Publication Number Publication Date
EP0505826A1 EP0505826A1 (fr) 1992-09-30
EP0505826B1 true EP0505826B1 (fr) 1995-04-05

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US (1) US5218291A (fr)
EP (1) EP0505826B1 (fr)
JP (1) JP2525963B2 (fr)
DE (1) DE69201897T2 (fr)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5315536A (en) * 1991-04-09 1994-05-24 Rohm Co., Ltd. Meter driving system
JPH0650992A (ja) * 1992-07-30 1994-02-25 Rohm Co Ltd メータ駆動装置
JP3278525B2 (ja) * 1994-02-28 2002-04-30 株式会社東芝 周波数データ変換装置およびメータ装置
JPH1172513A (ja) * 1997-08-28 1999-03-16 Nippon Seiki Co Ltd 指針指示計器

Family Cites Families (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5631652A (en) * 1979-08-24 1981-03-31 Nissan Motor Co Ltd Display unit for automobile
US4356445A (en) * 1980-07-10 1982-10-26 Cherry Semiconductor Corporation Method and apparatus for driving air core meter movements
US4485452A (en) * 1982-03-22 1984-11-27 The Bendix Corporation Speed measurement system
JPS63145969A (ja) * 1986-07-31 1988-06-18 Nippon Seiki Co Ltd 交叉コイル型可動磁石式計器
JPS6459162A (en) * 1987-08-31 1989-03-06 Japan Engine Valve Mfg Cross coil type mobile magnet instrument
JPH0711538B2 (ja) * 1988-02-05 1995-02-08 ジェコー株式会社 交差コイル式計器の駆動回路
JPH0675077B2 (ja) * 1988-11-24 1994-09-21 ローム株式会社 メータ駆動装置
US5142412A (en) * 1988-12-19 1992-08-25 Jaeger Circuit for controlling a ration meter
US4939675A (en) * 1988-12-22 1990-07-03 Chrysler Corporation Digital system for controlling mechanical instrument gauges
DE3927966A1 (de) * 1989-08-24 1991-02-28 Vdo Schindling Verfahren und schaltungsanordnung zur erzeugung einer eingangsgroesse fuer ein kreuzspulanzeigeinstrument
US5051688A (en) * 1989-12-20 1991-09-24 Rohm Co., Ltd. Crossed coil meter driving device having a plurality of input parameters

Also Published As

Publication number Publication date
JPH04296659A (ja) 1992-10-21
DE69201897D1 (de) 1995-05-11
DE69201897T2 (de) 1995-11-16
US5218291A (en) 1993-06-08
EP0505826A1 (fr) 1992-09-30
JP2525963B2 (ja) 1996-08-21

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